Ｏｂｊｅｃｔｉｖｅ　To observe the efficacy of femoral and sciatic nerve block in unilateral lower limb surgery in elderly patients.　Methods　Sixty ASAⅠ-Ⅲ patients aged 60 to 80 years， undergoing unilateral lower limb surgery were randomly divided into two groups（n=30）. In group A， the femoral and sciatic nerve was identified and blocked with 30 ml of 0.5% ropivacaine respectively guided with peripheral nerve stimulator. In group B， subarachnoid anesthesia was performed with 2 ml of 0.5% ropivacaine injected at spinal interspaces L2-3 or L3-4 before an epidural catheter was inserted for anesthesia maintenance. Blood pressure，heart rate and pulse oxygen saturation were monitored before anesthesia（T0） and 15（T1）， 30（T2）， 45（T3）， 60 min（T4） after anesthesia. The effectiveness of anesthesia and the incidence of adverse reactions were observed in both groups.　Results　There was no significant difference between the two groups in mean artery pressure（MAP） before anesthesia，while in group B， the MAP were decreased from （96±8） mmHg（1 mmHg=0.133 kPa） to （84±6） mmHg（P<0.01） at 15 min after anesthesia compaired to preanesthesia. The MAP in group A were（98±7） mmHg while（84±6） mmHg in group B（P<0.01） at 15 min after anesthesia and that at 30， 45 min after induction was also decreased（P<0.05）. There was no significant difference in the analgesia effects between the two groups. The incidence of adverse events （urinary retention， nausea and vomiting， etc.） was higher in group B（P<0.05）.　Conclusions　Femoral and sciatic nerve block is a safe and efficient technique with more stable hemodynamic status and less adverse events in elderly patients undergoing unilateral lower limb surgery.